Refrigeration controller



Nav. 19, 1940. w. E. WHHTNEY 2,222,210

REFRIGERAT ION CONTROLLER Filed Jan. 15, 1958 4 Sheets Sheet l Nov. 19,194%. W. E. m mM-EY I REFRIGERATION CONTROLLER Filed Jan. 15, 19384=-Sheets-Sheet 2 jya yaivw Nov. 19, 1940. w. E. wHrrNEY REFRIGERATIONCONTROLLER Filed Jan. 15, 1938 4 Sheets-Sheet 5 Nov. 19 1940. W. E.WHETNEY REFRIGERATION CONTROLLER 4 Sheets-Sheet File Jan. 15, lessPatented Nov. 19, 1940 JNITED STATES PATENT ()FFICE REFRIGERATIONCONTROLLER Application January 15, 1938, Serial N0. 185,193

21 Claims.

The present invention relates to an improved arrangement ofrefrigerating systems and of control devices suitable for refrigeratingsystems.

Certain refrigerating systems are heat operated and depend upon thecontinued input of heat to assure the maintenance of different pressuresin different parts of the system. For example, a system of the typedisclosed in the United States Patent No. 1,761,551 to Eastman A. Weaverpro- 0 vides an aspirator assembly for pumping refrigerant from a lowpressure evaporator to a condenser. In a system of this character, ifthe operation of the aspirator is nterrupted, as when the boilerpressure drops below a definite point,

the condenser and evaporator pressures are equalized by vapor flowingfrom the condenser to the evaporator. This vapor unnecessarily warms theevaporator and food compartment, thus reducing refrigerating efficiency.

so As disclosed in the copending application Serial No. 171,325 of LymanF. Whitney, now matured into Patent No. 2,180,447, refrigerating systemsof this character, which employ mercury as a propellant and which employan aqueous re 26 frigerant, may at times be characterized by thedevelopment of an objectionable or deleterious sludge. One factor whichmay cause the formation of such sludge is the flow of mercury vapordirectly from the aspirator assembly to the evap- 30 orator. Undernormal operating conditions, such "blow-back? of the propellant is anextremely unlikely occurrence, but it may occur when nor mal operationof the aspirator is about to be started or after such operation is interupted.

35 If a system of this character is regulated by a conventionalthermostatic control, the operation of the asp-irator may be frequentlyinterrupted, so that pressures in the condenser and evaporator may befrequently equalized and so that the w tendency't'oward sludge formationis increased.

The present invention provides a system of the general characterdescribed, with an associated control means normally effective inpermitting the continuous operation of the aspirator. Thus a; thepressure difference between the evaporator and condenser is maintained,sludge formation due to blow-back from the aspirator assembly into theevaporator is avoided, and refrigerating efficiency is also somewhatenhanced.

50 More particularly, the present invention permits the attainment ofthese desirable results with a refrigerator including an electricallyoperated heater. In addition, however, the present invention provides acontrol arrangement allowing the gradual variation in the average rateof electrical input to the system in response to the temperature of thefood compartment or the cooler without necessitating the waste ofelectricity by the use of rheostats or the like.

Further features of the invention relate to the provision of controlmeans to maintain a uniform temperature or the like under widely varyingconditions of operation and widely varying room temperatures, to permitmanual adjustment of the range of operation when desired, and par- 0ticularly, in the case of refrigerators, to afford means forautomatically terminating a defrosting period.

In one respect this invention involves clock mechanism or other timedmeans for varying en- M ergy input during recurrent periods of time orcycles, as by causing a heater to operate for a period in eachsucceeding three-minute cycle or the like, together with means forvarying the lengths of said periods in response to the tem- 2 peratureof the food compartment or other condition incident to therefrigeration. For example, under certain conditions of operation, thetimed means may cause the apparatus to operate during one minute out ofeach successive three-minute cycle, and under other conditions requiringmore refrigeration, the timed means may cause the apparatus to operateduring two minutes out of every three-minute cycle. Thus whileelectricity is supplied to the system at com stant voltage, the averagerate of supply may vary over a substantial period of elapsing time.Preferably the apparatus is controlled through the medium of an electricswitch with the timed means operating the switch, that is, opening and/or closing the switch, through the medium of a cam or the like.

In another aspect the invention involves a snap switch in a casing withan actuator extending outside the casing for actuating the switch, a camor other timed means for operating the switch during recurrent periodsof time, and thermostatic or other means for varying the length of theperiods by relative displacement of the easmg and cam with respect toeach other. Preferably the timed means operates on one contact of theswitch, as by engagement with said actuating member, and the thermostatoperates on the other contact of the switch, as by engagement with saidcasing, although both may oper- 5o ate on the same contact, as bycausing the thermostat to move the timed means and contact relatively toeach other or causing the timed means to move the thermostat and contactrelatively to each other. 56

In the preferred embodiment the switch casing is movably mounted with aspring or other yield- .ing means urging it toward the cam and thethermostat controls a stop which limits the movement of the casingtoward the cam. While the stop may be either advanced or retracted inresponse to increase of temperature, expansion of the thermostatpreferably advances the stop to shorten the length of the recurrentperiods of actuation of the switch by the cam.

In still another aspect this invention involves a movable switch and athermostat for moving the switch, together with a latch for holding theswitch out of operative relation to the thermostat and trip mechanismassociated with the thermostat and latch for restoring the operativerelationship when the temperature of the thermostat reaches apredetermined point.

For the purpose of illustration a typical embodiment of the invention isshown in the accompanying drawings in which Fig. l is a top plan view ofmy improved control device;

Fig. 2 is a rear elevation of the same with the parts in normaloperating positions and with the rear cover plate removed, a part beingshown in section;

Fig. 3 is a rear elevation of the same with theparts in defrostingposition and with the front cover plate omitted;

Fig. 4 is a rear elevation, with both the front and the rear coverplates removed, showing the parts in the positions which they occupyimmediately following defrosting;

Fig. 5 is an end elevation viewed from the lefthand end of the precedingfigures;

Fig. 6 is a section on line 6-6 of Fig. 2;

Fig. 7 is a plan view of the electric switch with the cover removed;

Fig. 8 is a plan view of the inside of the switch cover;

Fig. 9 is a side elevation of the switch assembly showing a part insection and showing a part of the switch operating lever; and

Fig. 10 is a diagrammatic view of a refrigerating system with which thecontrol device is combined, parts being shown in section.

The preferred control device chosen for the purpose of illustrationcomprises a front cover plate I, a rear cover plate 2, an angle member 3interconnecting the cover plates at the top, a

channel member 4 interconnecting the cover plates at the bottom, and apivot pin 5 bridging the space between the cover plates. Pivotallymounted on the pin 5 is a yoke 6 carrying between its legs an electricalswitch comprising a casing I, a cover 3, terminal screws 9 and I0, andan actuator 43, the casing being mounted in the yoke by means of screwsH and the cover being secured to the casing by means of screws l2 (Fig.2). The yoke 6 is yieldingly urged in a counterclockwise direction bymeans of a spring l3; and the counter-clockwise rotation of the yoke islimited by a stop controlled by a thermostat comprising bellows l4.

The aforesaid stop comprises a channel-shaped member l5 having itsflanges directed upwardly with the ends l6 of the flanges extendedupwardly to pivot the member on the pin 5, the extensions v|6 fittingbetween the ends of the yoke 6 as shown in Fig. 1. member I5 is aU-shaped yoke |l having upwardly extending arms IS in the path of thetwo legs of the yoke 6 and having a downward extension II which isL-shaped and which has fast Fast to the free end of the to the free endthereof a rounded bearing member |9. Fast to the right-hand end of themember l5 (Figs. 2, 3 and 4) is an arm which extends outwardly to aspring 2|, the spring serving to hold the member l5 against the contactbutton at the upper end of the bellows |4. As the bellows expandsupwardly it lifts the stop |5|||3 against the action of the spring 2|,and if the yoke 6 is seated against the upper ends l6 of the stop italso lifts the yoke against the action of spring l3. The bellows I4 isenclosed by sleeve 22 fast to the channel member 4 and the lower end ofthe bellows is provided with a nipple 23 for attachment to the fluidtube of the thermostatic system.

As shown in Figs. 5 and 6 the lower end of the bellows I4 rests on abifurcated lever 24 which is fulcrumed in the back plate 2 at 25 andwhich has an opening in its forward end for a rod 26. Threaded on thelower end of the rod is an adjustihg nut 21 seating upwardly against arecess in the lower side of the lever 24. The upper end of the rod 26 ispivoted at 29 to the lower end of an L-shaped member 29, the other endof which is pivotally mounted on the pin 5 as shown in Figs. 1 and 2.The under side of the member 29 is provided with a shoulder 30 uponwhich bears a cam 3| fast to the shaft 32 which carries on its outer endan adjusting knob (Fig. 1). By rotating the knob 33 the bellows I4 islifted by the lever 24 until the shoulder 30 drops off the end of thecam (Fig. 2) whereupon the bellows may again be lifted by continuedrotation of the knob 33 in the same direction.

Disposed between the switch 1-9 and the stop |5|| is an L-shaped lever34 having an upturned end pivoted on end 36 of the pin 5 (Figs. 1 and5). Beneath the free end of the lever 34 is a cam 35 rotating on a pin36 mounted in the front and back plates and 2 as shown in Figs. 1 and 5.Fast to the rear end of the cam 35 is a gear wheel 31 whose peripheryoverlaps the opening 38 in the back plate as shown in Fig. 3. The gear31 is driven by clock mechanism 39 (Figs. 5 and '6) mounted on the rearof the back plate 2 and having a shaft 40 extending forwardly throughthe opening 36 with a pinion on the end of the shaft meshing with thegear 31 (Fig. 3). Thus rotation of the cam 35 raises and lowers thelever 34 resting thereon.

As shown in Figs. 7, 8 and 9 the electric switch comprises a stationarycontact 4 I, a movable contact 42, a stop 54 and a plunger 43 actuatedby the lever 34 for moving the contact 42 from the contact 4| to thestop 54. As shown in Fig. 7 the contact 42 is bifurcated and the freeends associated with the contact 4| are, in the process of manufacture,slightly pinched together toward each other and held in this position bya cross strap 55, as well as being bent as shown in Fig. 9. Consequentlypressure on the contact 42 by the plunger 43 causes the contact 42 tosnap from the position shown in Fig. 9 to a position wherein the freeends of the contact 42 curve downwardly (Fig. 9) into engagement withthe stop 54, release of pressure by plunger 43 permitting the contact 42to snap back into the circuit-closing position shown in Fig. 9.

In the normal operation of the device the cam 35 opens the switchthrough the medium of lever 34 and plunger 43 once during eachrevolution of the cam, the switch remaining open for a period of timewhose length depends upon the position of the stop |5--|I as determinedby the thermostatic bellows N. If the bellows is expanded to raise thestop, the switch is opened for a short interval of time and if thebellows is contracted to permit the spring 2I to lower the stop theswitch is opened for a longer interval of time. After the cam has openedthe switch through the medium of the lever 34, the plunger 13 lifts theyoke 6 against the action of the spring For defrosting purposes thefollowing mechanism is provided. Pivoted to the frame member 3 at 44 isa depending L-shaped arm having a cam surface 46 at its lower end forcooperation with the bearing IS on the yoke I1 and having a lateral lug41 intermediate its ends. Journaled in the front plate I is a shaft 48having on its forward end an actuating knob 49 and on its rearward endan arm provided with a notch 5|, a shoulder 52 and a laterallyprojecting pin 53. When it is desired to defrost, the knob 49 is turnedto swing the arm 50 in a counterclockwise direction (Fig. 2) until thelug 41 drops into the recess 5|, the parts then occupying the positionsshown in Fig. 3. In swinging the arm 50 to defrosting position, the pin53 engages the switch-actuating lever 34, thereby opening the switch andlifting it to the position shown in Fig. 3. With the source of energyshut off from the refrigerating apparatus the bellows I4 gradually liftsthe yoke I'I-IB to the position shown in Fig. 4 whereupon the arm 45 isdisengaged from the arm 50 by engagement of'the bearing I9 against thecam surface 46. The arm 50 then swings back to its normal position shownin Figs. 2 and e and normal operation of the apparatus is resumed.

A control device of the type herein described may be employed incombination with various types of refrigerating systems such as motordriven apparatus. or apparatus provided with a fuel burning heater. Inthe latter case the switch I may control the heater by means of anelectromagnetic valve. A' control device of this type however isparticularly advantageous when combined with a refrigerating system ofthe type disclosed in the above-identified patent and when thecharacteristics of the control device and the systems are so co-relatedthat continuous operation of the aspirator assembly is normallypermitted. Especially when a system of this type is provided with anelectric heater, such a control device may be combined with the systemto effect continued operation of the aspirator without necessitating thewaste of electrical energy and while permitting extremely accurate conof the refrigerating apparatus in accordance with the temperature of thefood compartment and/or evaporator.

Fig. 10 discloses a system of this type which is provided with a boilerIOI affording a relatively large cylindrical recess for the reception ofa removable cartridge I02 containing an electrical resistance element.The boiler IOI may afford a thin mercury containing jacket about thesides and bottom of the cartridge receiving recess and may provide achamber I0I of substantial size above the cartridge, this chambercommunicating with the jacket. When electrical energy is supplied to theheating cartridge I02 mercury is vaporized in the boiler IM and theresulting vapor passes upwardly through the riser pipe I05 and itsbranches I05 and I05 to the first and second stage aspirator nozzles I06and H6 respectively. These nozzles form portions of aspirator assembliesI01 and II! respectively. The assembly I01 affords a mixing chamber I00connected by a vapor duct I09 to the upper part .of an evaporator IIOwhich contains a body of liquid refrigerant. A suitable aqueousrefrigerant such as water or a mixture of water with a suitableantifreeze agent such as methyl cellusolve and/or ethyl diamine may beprovided in the evaporator I I0. When mercury vapor issues from thenozzle I 06 at high velocity, the mixed vapors pass into a funnel IIIwhere the refrigerant is compressed and mercury is condensed. Thecompressed refrigerant vapor passes from the lower end of the funnel I II into an interstage cooler I20 which is provided with cooling meanssuch as flns H3. The vapor passes from the interstage cooler I20 througha duct I I4 to a connection with the mixing chamber II8 of the secondstage aspirator assembly where the mercury vapor from the nozzle H6 iseffective in further pumping and'comvpressing the refrigerant vapor asit passes through the funnel I2 I. The compressed refrigerant vaporflows upwardly from this funnel through a duct I22 to a refrigerantcondenser I23 which may conveniently be disposed at the upper part ofthe system. I

The aspirator assemblies are provided with jackets I I 5 and I25 whichmay contain a suitable volatile coolant, such as alcohol or a mixture ofalcohol with a minor percentage of acetone. Ducts I30, and I30 extendupwardly from the jackets I I5 and I 25 respectively to receive alcoholvapor therefrom, the upper parts of these ducts being provided withcooling fins and thus affording condensers which form heat dissipatorsfor the funnels. In order to facilitate the dissipation of heat throughthese condensers, the ducts I30 and I34) may preferably be evacuated sothat substantially all of the air is removed therefrom. For this purposesuitable evacuating and sealing connections I33 may be connected tochambers I3I and II3I at the upper ends of the ducts I30 and I30respectively. The chambers I3I and I3I increase the volumetriccapacities of the vapor-containing portions of the heat dissipators andmake the same less sensitive to minor leakages of air.

The refrigerant condenser I23 is also provided with an evacuating andsealing connection I33 similar to the connections I33, so that therefrigerating system may be evacuated when it is installed and so thatthe evaporator I I0 may operate at a low absolute pressure. For example,the

pressure in the evaporator may be of the order of 4 mm. absolute at 0 C.

The condenser I23 is provided with any suitable cooling means such asheat dissipating fins and its lower end is connected to a return ductI35 providing one leg of a trap I36, the opposite leg of which isconnected by a short duct I31 to the evaporator H0. The trap I36 maycontain a body of the propellant e. g. mercury, and the pipe I35 isarranged so that the condensed refrigerant piles up in a column abovethe mercury in the trap until some of the refrigerant can pass throughthe trap and thus return to the evaporator. It is evident that themercury in trap I36 is effective in substantially balancing thedifference between the evaporator and condenser pressures.

Condensed mercury may be received from the first stage funnel by a drainI40 which is connected to a drain I receiving mercury from the secondstage funnel. Drain I42 receives condensed mercury from the first stagehead I08 and is connected to a drain I43 receiving mercury from thesecond stage head I I8. The lower part of the drain I43 is connected tothe drain I. The lower part of the latter is connected to the bottom ofthe boiler IN and contains a column of mercury to balance the boilerpressure.

A trap I is connected to the bottom of the evaporator IIO to receivestray mercury particles therefrom and the opposite leg of this trap hasa connection I5I with the duct I43.

Electric energy may be supplied to a system of this character by leads Iand I6I, the latter being connected directly to one side of thecartridge I02 having a branch I62 connected to one side of the clock 39of the control device shown in Figs. 1 to 9. The opposite side of thisclock is connected by a lead I63 to the lead I60. The lead I60 isconnected to one side of the switch I as shown in Fig. 9 and a lead I65extends from the opposite side of the switch to the cartridge I02.

The bellows I4 is connected by a tube I61 to a thermostatic bulb I60which may be arranged in the food compartment and in the region ofevaporator IIO. Accordingly the pressure within the thermostatic devicei. e. the bulb I68, tube I0! and bellows I4, varies in accordance withthe temperature of the food compartment and the evaporator. When thistemperature increases the pressure within the thermostatic device causesthe bellows I4 to expand thus lifting the member I5 so that the switch Iis opened for a smaller fraction of each cycle of the control devicecorresponding to each revolution of the cam 35. Thus, under theseconditions, the portion of the operating cycle during which heat issupplied to the boiler IN is increased and accordingly over asubstantial period of time, the average electrical input iscorrespondingly increased. It is evident that the switch I as shown maybe arranged directly in series with the cartridge I02 so that when theswitch is closed, heat is being supplied to the mercury within theboiler IOI.

The boiler IN and the aspirator assemblies I01 and I I! preferably areenclosed in a suitable heat insulating casing comprising a metal housingII0 containing discrete insulating material III. Thus during the shortintervals during which the supply of current to the cartridge I02 isinterrupted. there is but a slight change in the temperature of themercury circuit and of the boiler. The mercury containing portions ofthe refrigerating system and the various factors of the control deviceaccordingly may be so interrelated that under normal operatingconditions i. e. when the room temperature is above 60 F. continuousoperation of the aspirator assembly is maintained despite the frequentinterruptions to the input of electrical energy. Thus between successiveswitch-closing periods there may be only a moderate decrease in thepressure within the boiler IN and a corresponding moderate decrease inthe height of the pressure balancing column of mercury in the lower partof pipe I. Since the aspirator assemblies operate continuously undersuch conditions, even if electrical energy is being supplied at anaverage rate of the order of onehalf of the maximum rate, the differencebetween the evaporator and condenser pressures is maintained and hotvapor is prevented from flowing through the aspirator assembly into theupper part of the evaporator, Thus unnecessary heating of the evaporatoris avoided. Furthermore continuous operation of the aspirator assemblyin such a manner assures continuous flow of mercury vapor into thefunnel III and blow-back of the mercury vapor through the duct I00 intothe evaporator H0 is accordingly avoided. Thus a tendency to form sludgewhich might otherwise be present is eliminated.

Furthermore the control device permits a very slight variation in theaverage amount of energy being supplied to the cartridge I02 and theboiler IOI in response to a small change in the temperature of the bulbI60, so that a very close and accurate control of the refrigeratingsystem is afforded. As a consequence the maximumpressures within thesystem may be lower than would be the case with an intermittentlyoperating system. If a system of the present type were to be providedwith a conventional thermostatic control effective to cause theoperation of the aspirator assembly for a period of substantial lengthand then interruption of such operation for a period of substantiallength, higher boiler pressures would be necessary than with the presentarrangement. Such a higher boiler pressure might result in anappreciable noise 'when the system first resumed operation. The presentarrangement however avoids such a disadvantage.

Preferably the thermostatic device I4-I 6|--I68 may be so arranged incombination with the remainder of the control device that underpractically any room temperature, 1. e. even a temperature as low as 45F. the switch I is closed for at least some period of each operatingcycle and under normal room temperature i. e. a temperature of above 60F. the switch-closing fraction of the cycle is long enough to assureuninterrupted operation of the aspirator assembly. Thus the minorfluctuations in boiler pressure which take place between successiveswitch-closing periods of successive cycles are insufllcient to causefluctuations in the boiler pressure of as much as 15%. In fact. underusual operating conditions, the boiler pressure may fluctuate less than5% during a complete cycle.

It is thus evident that the present invention permits the continuousoperation of a refrigerating system of the aspirator type at normal roomtemperature, thus avoiding unnecessary heating of the evaporator andreducing the likelihood of sludge formation. It is furthermore evidentthat the present invention aflords an unusually sensitive and accuratecontrol for the refrigerating apparatus, which avoids the undesirablelag which is characteristic of a device wherein a switch is directlyopened and closed by a thermostatic device. It is furthermore evidentthat a device of this character permits the close and accurateregulation of the average rate of supply of energy to the system withoutnecessity for wasting electricity as would be the case were a rheostator rheostats employed.

While for the purpose of illustration, I have disclosed herein a simplerefrigerating system embodying the principles of the present invention,it is to be understood that a more highly developed system such as thatshown 'in the above-identified co-pending application can be combinedwith my improved control device to atford the same desirable results. Itis furthermore evident that if desired, a relay may be controlled by theswitch I in order in turn to control the supply of energy to the heaterI02.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

- accordance with the condition of the tempera- I claim:

1. Refrigerating apparatus of the heat-operated type comprising anelectric heater, a refrigerant circuit including a cooler through whichrefrigerant is circulated in response to operation of the heater, aswitch controlling the flow of electricity to said heater, a controllerfor the switch operable in brief repetitive cycles each including aswitch closing period, and a thermostatic device to vary the effect ofthe controller on the switch in accordance with the temperature of theregion of the cooler so that the lengths of intervals between saidperiods in successive cycles increase and decrease respectively as thetemperature of said region falls and rises, the maximum lengths of saidintervals being so short that continuous, uninterrupted circulation ofthe refrigerant is normally maintained.

2. Refrigerating apparatus comprising a cooler, a condenser, anaspirator for pumping refrigerant vapor from the cooler to thecondenser, a boiler for supplying propellant vapor to the aspirator, anelectric heater for said boiler, and controlling means for said heaterresponsive to thetemperature of the region of the cooler for supplyingelectricity to said heater at constant voltage but at a varying averagerate dependent upon the temperature of said region, the minimum averagerate being high enough to maintain continuous, uninterrupted pumping ofrefrigerant in the aspirator.

3. Refrigerating apparatus comprising a refrigerant circuit including acondenser and a cooler containing a body of liquid refrigerant, apropellant circuit including a boiler and an aspirator where refrigerantvapor is pumped from the cooler to the condenser, said boiler containinga body of propellant fluid which, upon straying to the cooler, mayinteract with the refrigerant to form a deleterious sludge, an electricheater for said boiler, a switch controlling the fiow of electricity tosaid heater, a controller for the switch operable in brief repetitivecycles, and thermostatic means responsive to the temperature of theregion of the cooler for varying the effect of the controller on theswitch so that the switch is closed during a period in each cycle, theduration of which depends upon the temperature of said region, theintervals between said periods being so short, that continuous,uninterrupted circulation of the refrigerant is normally maintained bysaid aspirator, whereby automatic control of refrig eration is affordedbut direct flow of propellant vapor to the cooler is substantiallyprevented, thus impeding sludge formation in the cooler.

4. Refrigerating apparatus comprising a refrigerant circuit includ ng acondenser and a cooler containing a body of liquid refrigerant, apropellant circuit including a boiler and an aspirator for pumpingrefrigerant vapor from the cooler to the condenser, said refrigerantcircuit being open and uninterrupted between the cooler and condenserand the pressure of the propellant vapor normally being elfective inmaintaining a higher pressure in the condenser than in the cooler, anelectric heater for said boiler, a switch controlling the flow ofelectricity to said heater, and control means for said switch includingan element responsive to the temperature of the region of said cooler,said means being effective in closing and opening said switch duringbrief recurrent cycles controlled so that the total fraction ofclaps-ing time during-which the switch is closed varies in tureresponsive element, the lengths of intervals of interruption to the flowof electricity to the heater being so short that operation of saidaspirator is not interrupted and accordingly flow of refrigerant vaporfrom the condenser to the cooler is not permitted.

5. Method of refrigeration comprising supplying electrical energy tovaporize a propellant, entraining refrigerant vapor from a body ofliquid refrigerant in a stream of the resulting propellant vapor andpumping the refrigerant vapor to a region of higher pressures, whilesupplying electrical energy to vaporize the propellant at constantvoltage but in brief recurrent periods, varying the total fraction ofthe elapsing time occupied by said periods in accordance with thetemperature. of the region of said body, thereby to maintain thetemperature of the region of said body within close limits, butmaintaining said fraction great enough and intervals between saidperiods short enough to assure continuous pumping of the refrigerant.

6. Refrigerating apparatus comprising a refrigerant circuit including acondenser and a cooler containing a body of liquid refrigerant, apropellant circuit including a boiler and a part in common with therefrigerant circuit where propellant vapor is effective in entrainingand compressing refrigerant vapor, said propellant circuit alsoincluding a duct extending downwardly to the boiler and normallycontaining a column of liquid propellant to balance the boiler pressure,an electric heater for said boiler, a switch controlling the flow ofelectricity to said heater, and control means for said switch includingan element responsive to the temperature of the region of said cooler,said means closing and opening said switch during brief recurrent cyclescontrolled so that the height of said column fluctuates less than 15%during a single cycle.

7. A circuit controller comprising a casing, a snap switch within thecasing, an actuator extending outside the casing for actuating theswitch, means for operating said actuator during recurrent periods oftime, and thermostatic means for varying the length of said periods byrelative displacement of said casing and means with respect to eachother.

8. A circuit controller comprising a switch casing, a snap switch insidethe casing, a switchactuating member extending through the casing, meansfor actuating said member during successive periods, a support for saidcasing, said casing and means being relatively movable to vary theduration of said periods by changing the operative relationship betweensaid member and means, means yieldingly tending to change saidrelationship, and an adjustable stop limiting the action of said means.

9. A circuit controller comprising a switch casing, a snap switch insidethe casing, a switchactuating member extending through the casing, meansincluding a cam for actuating said member, a support for said casing,said casing and cam being relatively movable to vary the operativerelationship between said member and cam, a spring tending to changesaid relationship, and a thermostatic stop limiting the action of saidspring.

10. A circuit controller comprising a switch casing, a snap switchinside the casing, a switchcessive periods, a support for said casing,said casing and means being relatively movable to vary the duration ofsaid periods by changing the operative relationship between said memberand means, a bearing member between said member and means which ismovable relatively to said casing and means, means yieldingly tending tochange said relationship, and an adjustable stop limiting the action ofsaid last means.

11. A circuit controller comprising a switch casing, a snap switchinside the casing, a switchactuating member extending through thecasing, means for actuating said member during successive periods, apivotal support for said casing, said casing and means being relativelymovable to vary the duration of said periods by changing the operativerelationship between said member and means, a pivotedbearing memberbetween said member and means which is coaxial with said pivotalsupport, means yieldingly tending to change said relationship, and anadjustable stop limiting the action of said last means.

12. A circuit controller comprising a switch casing, a snap switchwithin the casing, a switchactuating plunger extending through thecasing, a cam rotatable about an axis for actuating said plunger duringsuccessive periods, a movable support for said casing for varying theduration of said periods by moving said plunger toward and from saidaxis, a spring urging the casing toward the cam, and an adjustable stoplimiting the action of said spring.

13. A circuit controller comprising a switch casing, a snap switchwithin the casing, a switchactuating plunger extending through thecasing, a cam rotatable about an axis for actuating said plunger duringsuccessive periods, a movable support for said casing for varying theduration of said periods by moving said plunger toward and from saidaxis, a spring urging the casing toward the cam, a stop for limiting theaction of said spring, and a thermostat for moving said stop counter tosaid spring in response to increase of temperature.

14. A circuit controller comprising a switch casing, a snap switchwithin the casing, a switchactuating plunger extending through thecasing, a cam rotatable about an axis for actuating said plunger duringsuccessive periods, a movable support for said casing for varying theduration of said periods by moving said plunger toward and from saidaxis, a spring urging the casing toward the cam, and a thermostatic stoplimiting the action of said spring.

15. A circuit controller comprising a switch casing, a snap switchwithin the casing, a switchactuating plunger extending through thecasing, a cam for actuating said plunger during successive periods, apivotal support for said casing for varying the duration of said periodsby moving said plunger toward and from the cam, a spring urging thecasing toward the cam, a pivoted stop coaxial with said support forlimiting the action of said spring, and means for swinging said stopcounter to said spring thereby to move said plunger away from said-cam.

16. A circuit-controller comprising a switch, a movable support for theswitch, a thermostat for actuating the switch, timed means ior actuatingthe switch periodically, a latch for said support to hold the switch outof operative relation to said thermostat and timed means, and tripmechanism associated with said thermostat and latch for restoring saidoperative relationship of the switch to both thermostat and timed meanswhen the temperature of the thermostat reaches a predetermined point.

17. A circuit controller comprising a switch, a movable support for theswitch, a thermostat for actuating the switch, means yieldingly urgingthe switch toward the thermostat, a stop for limiting the action of saidmeans, the thermostat acting on the switch through the medium of saidstop, a latch for said stop to hold the switch out of operative relationto the thermostat, and trip mechanism associated with said thermostatand latch for restoring said operative relationship when the temperatureof the thermostat reaches a predetermined point.

18. A refrigeration controller comprising a cover plate, means normallyconcealed by said plate for increasing refrigeration during recurrentperiods of time, means for varying the length of said periods inresponse to the conditions of refrigeration, and means for adjustingsaid last means including a manually movable part disposed outwardly ofsaid cover plate.

19. A circuit-controller comprising a switch casing, a snap switchinside the casing, a switchactuating member extending through thecasing, a cam for actuating said member during successive periods, asupport for said casing, said casing and cam being relatively movable tovary the duration of said periods by changing the operative relationshipbetween said member and cam, means yieldingly tending to change saidrelationship, a stop limiting the action of said means, and an automaticregulator for moving said stop.

20. A circuit controller comprising a switch casing, a snap switchinside the casing, a switchactuating member extending through thecasing, means for actuating said member, a support for said casing, saidcasing and cam being relatively movable to vary the operativerelationship between said member and cam, a spring tending to changesaid relationship, a stop limiting the action of said spring, anautomatic regulator for moving said stop, and means for manuallyadjusting the stop through the medium of said regulator.

21. Refrigerating apparatus of the heat-operated type comprising anelectric heater, a refrigerant circuit including a cooler through whichrefrigerant is circulated in response to operation of the heater, acircuit controller for said heater comprising a switch, a movablesupport for the switch, a thermostat for actuating the switch, timedmeans for actuating the switch periodically, a latch for said support tohold the switch out of operative relation to said thermostat and timedmeans, and trip mechanism associated with said thermstat and latch forrestoring said operative relationship of the switch to both thermostatand timed means when the temperature of the thermostat reaches apredetermined point.

WILLIAM E. WHITNEY.

